Various portable electronic devices have user interfaces to enable interaction with a user. The user interface of portable devices is often a compromise between mutually conflicting design objectives related to cost, complexity, accessibility, intuitiveness and compactness. Mobile phones typically sport a display and one or more keys on a common side so as to enable displaying of information and input of data from the user. The display may be a touch display in which case fewer keys are needed.
Some mobile phones have a clam-shell form factor in which the phone when opened reveals on its two internal walls a display and keypad, respectively. Another form factor is a monoblock model in which there is a display and some keys which occupy most of one side of the phone. There are also slide phones with a user interface that is extended by sliding apart a display part and a keypad part.
Game controllers of different game stations are specifically designed for comfortable grip and access to controls. Such controllers typically have an arcuate form and such a size that they suitably fill the hand when gripped by a user. However, the game controllers' design makes their placing in the user's pocket difficult or impossible. There are also some mobile phones designed particularly for gaming, with keypad arrangement on a front surface around the display so dimensioned and laid out that the user should be able to reasonably access the keys.